Method and apparatus for electrostatically applying flock to filament material



w. LINNEBoRN 3,375,124 METHOD AND APPARATUS FOR ELECTHOSTATICALLYAPPLYING FLOCK TO FILAMENT MATERIAL 5 Sheets-Sheet 1 8 5 6 e 9 w l 1 7 62 v O h N C d Y. a m .1 M F Figp/ March 26, 1968 w. UNNEBORN 3,375,124

METHOD AND APPARATUS FOR ELECTROSTATICALLY APPLYING FLOCK TO FILAMENTMATERIAL Filed Nov. 7, 1963 3 Sheets-Sheet 2 Fig. 3

United States Patent ice METHOD AND APPARATUS FOR ELECTRO- STATICALLYAPPLYING FLOCK T FILA- MENT MATERIAL Walter Linneborn, Monschauer-Platz,Cologne, Germany Continuation-in-partof application Ser. No. 11,929,Feb. 29, 1960. This application Nov. 7, 1963, Ser. No. 322,092

Claims. (Cl. 117-17) ABSTRACT OF THE DISCLOSURE Method and apparatus forapplying flock under the influence of electrostatic fields produced bytwo electrodes positioned in a grounded conductive enclosure. Means formoving adhesive-coated filament material at substantially groundpotential in longitudinal direction thereof along a predetermined paththrough a treatment zone within the enclosure. Negatively chargedsupport means arranged below the predetermined path spaced therefrom intransverse direction and adapted for carryin-g flock material particles.Aperture-defining first electrode means through which the particles areadapted to pass, and arranged to apply an electrostatic charge to suchparticles, the first electrode means being located between the supportmeans and the filament material. Means for establishing between thesupport means and the first electrode means a first electrostatic fieldhaving a first gradient in the transverse direction for effectingmovement of the flock material particles in suchv transverse direction.Second electrode means in the encolsure located above the path insubstantial parallelism therewith and arranged to apply an electrostaticcharge to the flock particles, and means for establishing between thefirst and second electrode means a second electrostatic field having asecond gradient opposite to the first gradient.

This application is a continuation-in-part of my previous applicationSer. No. 11,929, filed on Feb. 29, 1960, for Electrostatic Coating ofCord-Like Products, and now abandoned.

The present invention concerns the application of flock material tofilament type material and more particularly a method and apparatus forelectrostatically applying flock material, particularly short pieces offibrous material, to adhesive-coated filament material which includesyarns, threads, wires and any other elongated bodies having acomparatively small diameter relative to their length.

Many attempts have been made in the past to apply flock materialelectrostatically to adhesive-coated filament material. However, theresults of the known methods and arrangements have not beensatisfactory, mainly for the reason that the applied flock material wasnot more or less uniformly distributed around the entire circumferenceof the filament material, but appeared rather to be accumulated more onone side of the filament material than on the opposite side thereof.

It is therefore one object of this invention to provide for a method andapparatus for electrostatically applying flock material toadhesive-coated filament material While avoiding the unsatisfactory-results of the known method and apparatus.

It is another object of this invention to provide for a Amethod andapparatus as set forth which are applicable to various kinds of filamentmaterial no matter whether conductive or non-conductive.

It is still another object of this invention to provide for a method andapparatus as set forth which is comparatively simple in operation andentirely satisfactory and efficient in its results.

3,375,124 Patented Mar. 26, 1968 With above objects in view theinvention includes a method of electrostatically applying flock materialto adhesive-coated material of a diameter comparatively small relativeto its length, comprising the steps of: orienting the adhesive-coatedmaterial longitudinally in a predetermined direction along apredetermined area of treatment, introducing particles of flock materialinto a region extending substantially parallel with the predetermineddirection and spaced in transverse direction from the adhesivecoatedmaterial, subjecting the particles of flock material to a high potentialfirst electrostatic field so directed that the particles of flocklmaterial are moved with substantial acceleration in the transversedirection ltoward the adhesive-coated material so that those of theparticles Which make contact with the adhesive-coated material areattached thereto due to the action of the adhesive coating thereof whilethose other particles which have missed the adhesive-coated material aremoved due to the kinetic energy imparted thereto beyond and past theadhesivecoated material, and subjecting the other particles of flockmaterial which have been moved beyond the adhesive-coated material to atleast one other electrostatic field so directed that the other particlesare caused to reverse their direction of movement and to move inopposite direction toward the adhesive-coated material so that those ofthe other particles which make contact with the adhesive-coated materialare attached thereto due to the action of the adhesive coating while theremaining ones of the other particles which have again missed theadhesive-coated material are caused to be again subjected to the actionof the first electrostatic field.

In another aspect the invention also includes an apparatus forelectrostatically applying flock material to adhesive-coatedfilamentmaterial, comprising, in combination, housing means, moving means formoving adhesive-coated filament material in longitudinal directionthereof along a predetermined path through a predetermined zone oftreatment located within the housing means, means for applying to thefilament material substantially ground potential, at least partlyconductive support means arranged in the housing means and extendingsubstantially parallel with and underneath the predetermined path andspaced therefrom in transverse direction a predetermined distance, forcarrying flock material on its top surface, means for applying negativepotential to the support means, grid-type electrode means extendingsubstantially parallel with the top surface of the support means andsubstantially midway between the latter and the predetermined path ofthe filament material, means for applying high positive potential tosaid grid-type -electrode means so as to establish a first electrostaticfield between the support means and the first electrode means and havinga first gradient in the transverse direction and so directed that flockmaterial particles are moved from the support means with substantialacceleration across the grid-type electrode means toward the filamentmaterial so that those particles which make contact therewith areattached thereto while those other particles which have missed thefilament material are moved beyond and past the latter, second electrodemeans extending in the housing substantially parallel with and above thepre-determined path of the filament material and spaced therefrom apredetermined distance in the transverse direction, and means forapplying negative potential to the second electrode means so as toestablish 'a second electrostatic field between the first and secondelectrode `means and having a second gradient opposite to the firstgradient and so directed that the `other flock material particles arecaused to reverse the 'direction of their movement and to move inopposite direction toward the filament material so as tot be attachedthereto as far as they make contact therewith, while those of the otherparticles which miss the filament material again are caused to be againsubjected to the action of the first electrostatic field.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to itsconstruction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. l is a partly sectional elevation of an apparatus according to theinvention, the section lbeing taken along line I--I of FIG. 2;

FIG. 2 is a partly sectional end View of the apparatus according to FIG.l, the section being taken along line II-II of FIG. l;

FIG. 3 is a partial plan view of 4one of the electrodes of the apparatusaccording to FIGS. l and 2; and

FIG. 4 is a diagram related to the elevation of FIG. 1 and illustratingthe execution of the method according to the invention and the operationof the illustrated apparatus.

As can be seen from FIGS. 1 and 2, the apparatus comprises a mainhousing .1 which surrounds all the operating main components of theapparatus and includes a storage and distribution Iportion 2. The entirehousing is constructed as a Faraday cage i.e. it is made predominantlyof conductive material and is connected to ground potential at 1". Thefront and rear walls of the housing 1 are provided each with an opening1' of rectangular shape as will be described further below.

The storage and distribution portion 2 of the housing 1 serves for theintroduction of the fiock material. The portion 2 is separated from theremainder of the housing 1 and is equipped with a funnel 27 for feedingflock material into the interior of the portion 2, a shutter 28 beingprovided for closing the inlet duct. A rotating distributor brush device3 with a plurality of arms 4 is rotatably supported in the housingportion 2 and is driven vin a conventional manner by a motor 10 via aspeed reduction gear 9 and chain transmissions as illustrated. Theindividual arms 4 of the brush device 3 may be provided with individualbrushes, bristles or with lips or wipers made of rubber or syntheticmaterial so as to brush uniformly over the sieve-like bottom 5 of thehousing portion 2 so that any flock material located in the housingportion 2 will be .gradually brushed through the sieve-like bottom 5. Inorder to render this operation even more effective the center portion 6of the sieve-like bottom 5 is movable in horizontal direction. Thismovement is effected by the cooperation of a cam follower 6 attached tothe movable portion 6 with a rapidly rotating cam 7 driven through theabove-mentioned transmission means also by the motor 10. The sieve-likebottom 5 is suspended on springs as illustrated and is subjected tovertical vibration by the action of auxiliary cams 7' driven inconjunction with the cam 7. Consequently, this vibration movement issuperimposed on the reciprocating movement of the center portion 6,which together with the action of the brush device 3 causes the flockmaterial to pass uniformly through the sieve-like bottom 5, 6 of thehousing portion 2.

Extending from a point underneath the sieve-like bottom S in horizontaldirection through the housing 1 is an endless `conveyor belt 8 which ismade at least predominantly of conductive material and which is inconductive connection with the housing 1 so that the conveyor 8 carriesground or negative potential. 'Ille conveyor 8 is also driven by themotor 10` via the infinitely variable gear transmission 9 and the othertransmission means. It is evident that the fiock material passed throughthe sieve-like bottom 5, 6 is received by the conveyor 8 and transportedin the direction of the arrow in horizontal direction into and throughthe housing 1. During the travel of the fiock material on the conveyor 8through the housing -1 the majority of the flock material particles islifted off the conveyor 8 and applied to the filament material as willbe described further below. Whatever flock material is left on theconveyor 8 at its remote end is dropped into a hopper 16 whichdischarges this material into the intake conduit of a blower 17 alsodriven by the motor 10 so that this excess material is blown through theduct 18 back into the housing portion 2 for being reintroduced into theoperational cycle. The air conveyed through the duct 18 into the housingportion 2 is permitted to escape through a closure 19 which is permeableto air. This closure 19 may consist of an accordion-pleated fabric whichis kept in position by rods 20. A twoarm lever tiltably mounted at 21 isso constructed that its lever arm 22 projects into the rotary path ofthe arms 4 of the brush device 3 so that during the rotation of thebrush device 3 the arm 22 is periodically engaged by the arms 4 with theresult that the other arms 24, 25 and 26 periodically strike the fabricof the closure 219 and cause any flock material that may have settledthereon under the action of the air blow to fall back into the housingportion 2.

The filament mate-rial to be covered with fiock material may consist inthis example of a plurality of threads of cords 2.9 which are alloriented in a horizontal plane, spaced from each other and guided inhorizontal direction through the above mentioned lateral openings 1 ofthe housing 1 and consequently through the housing 1 at a predetermineddistance above the top surface of the conveyor 8. The filaments 29 maybe unwound from a reel or reels 32 and pulled through a container 31grounded at 31 and containing a liquid adhesive 31 so that the filaments29 pass in adhesive-coated condition through the apparatus for beingcovered with flock material therein, Whereafter the filaments 29 may bewound on a take-up reel or reels 33 in a conventional manner. Since thead hesive container 31 assumed to be of conductive material is groundedand since the adhesive itself may be considered to be conductive, andsince also the guide rollers guiding the filaments 29 can be assumed tobe conductive and connected conductively with the housing 1, it is fairto assume that the filaments 29 carry quasi-ground potential. Should thefilaments 29 be made themselves of conductive material then theycertainly would carry a potential substantially equal to ground ornegative potential.

Extending substantially parallel with the path of the filaments 29 andlocated substantially midway in transverse direction between the topsurface of the conveyor 8 and the path of the filaments 29 is arranged agrid-type electrode 11 as illustrated separately by FIG. 3. The mesh orgrating of this electrode 11 is made of conductive material and is heldin a frame 11' made of insulating material. The conductive electrodematerial of the electrode 11 is connected by an insulated connection 34with a terminal of a source of high positive potential. Consequently, astrong electrostatic field with a gradient in the abovementionedtransverse direction is set up between the top surface of the conveyor 8carrying negative or ground potential and the electrode grid 11 carryinghigh positive potential. The function of the electrode 11 will bedescribed further below. It should be noted that the electrode 11 orrather its frame 11' is suspended resiliently from the side walls of thehousing 1 as illustrated at 11". By cooperation of the frame 11 withpairs of cams 12 and 13 rotatably supported in the housing 1 as shown inFIG. 2 and driven also by the motor 10 in the same manner as the cam 7the electrode 11 is subjected to vibratory movement in order to shakeloose any ock material particles which may tend to settle on the grid ofthe electrode 11.

A second grid-type electrode 30 is arranged at a predetermined distanceabove the plane containing the paths of the filaments 29 and extends ina substantially horizontal plane as illustrated. The grating of theelectrode 30 may be similar to that of the electrode 11 except that theopenings or perforations thereof may be smaller than those of theelectrode 11 and except that the frame 30" holding the grating of theelectrode 30 need not be made of insulating material. To the contrary itis desirable to make it of conductive material like the entire electrode30 so that through the resilient suspension members 30 supporting theframe 30" ground or negative potential is applied to the electrode 30.Consequently, at least one further electrostatic field is set up betweenthe first gridtype electrode 11 carrying high positive potential and thesecond grid-type electrode 30 carrying negative or ground potential.Pairs of cams 14 and 15 similar to the cams 12 and 13, are provided forcooperation with the frame 30 and are also driven in conjunction withthe cam 7 so that in this manner also the grid-type electrode 30 issubjected to vibration in order to shake off any fiock materialparticles that may settle on the grating of the electrode 30.

It must not be overlooked that also potential differences exist betweenthe first grid-type electrode 11 and the opposite wall portion of thehousing 1 located above the second grid-type electrode 30, and that,depending upon the actual potential existing on the filaments 29additional potential differences exist between these filaments 29, theindividual electrodes 11 and 30, the conveyor 8 and the above-mentionedwall portion of the housing 1. All these potential differencesnecessarily serve to establish corresponding electrostatic fields ofcorrespondingly differing strengths. The existence of these differentfields influences in various ways the operation of the apparatus and theaction on the flock material particles in accordance with the methoddevised by the invention.

In carrying out the method according to the invention and in operatingthe apparatus as described above by Way of example, the procedure is asfollows: As is already implied by the above description of theapparatus, ock material is introduced into the housing portion 2 and theock material particles are continuously fed onto the top surface of theconveyor 8 and carried -by the latter through the interior of the'housing 1. Simultaneously, filament material is unwound from the stockreel 32 and pulled through the adhesive container 3:1 so as to be coatedwith adhesive and moved continuously through the interior of the housing1 in the direction of the arrow in FIG. 2 for being subsequently Woundon the take-up reel or reels 33. The action of the electrostatic fieldsestablished in the apparatus will now be explained in full detail byreference to FIG. 4. FIG. 4 is to be considered only as a diagramindicating the positional relations and distances between the topsurface of the conveyor 8, the electrodes 11 and 30, the plurality offilaments 29 and the top wall of the housing 1. Also, this diagramindicates the polarities of the electric potentials applied .to theabovementioned portions of the arrangement (as indicated at the lefthand side of the diagram) and also the various electrostatic fields setup on the basis of the existing potential differences lbetween theabove-mentioned components of the arrangement.

The various fields are marked with the rom'an numerals LVII. Whereverwithin the diagram a marking occurs like II-VII this does not mean torepresent the difference between the strength of the fields II-VII, butmeansfthat at the particular point all the fields numbered II to VIIexert their inuence. In a similar manner, where in the diagram anindication occu-rs like IV-i-VI .this does not mean ythat here the twofields IV and VIv are additively superimposed upon each other but thismeans only that at the particular point both the fields IV and VI exerttheir effect.

For the purpose of explanation only the entire horizontal length of thediagram is subdivided into sectors numbered l to 20 so that differentphenomena that may occur anywhere within the existing electric fieldsmay be described with reference to specific illustrations in the,individual sectors mentioned above.

May it be assumed that it is desired to describe what happens to a fiockmaterial particle A which is placed on the conveyor 8 and introducedinto the area of treatment at the right hand end of the diagram. Sinceit is proper to assume that this particle A is electrically neutral itis shown as an empty rectangle lying fiat on the surface of the conveyor8.

Sector I As soon as the particle A enters the sector 1 it is exposed toand influenced by .the strong electrostatic field I existing lbetweenthe conveyor 8 and the positively charged electrode 11 so that theparticle A is oriented in vertical direction, i.e., in direction of theexisting gradient and is accelerated in vertical direction.

Sector Z After the particle A has been set in motion there are only twopossibilities. The first possibility is that the particle A dartsthrough one of the openings of the grid-type electrode 11, the other isthat it hits one of the grid wires or the like as is shown in sector 17.The particle which, as shown in sector 2, passes through an opening ofthe positively charged grid-type electrode 11 is thereby charged itselfto positive potential under the infiuence of the field I. Therefore, insector 2 the particle A is shown as a solid black rectangle. Referringnow also to sector 17, it will be understood that upon hitting a gridwire of the electrode 11 the particle A is also charged to positivepotential with the result that it now possesses the same polarity as theelectrode 11. Consequently, the particle A in sector 17 is subject totwo forces, namely to the force of repulsion K from the electrode 11 andto the force of gravity G. Consequently, this charged particle A dropsback onto the top surface of the conveyor 8 as shown in sector 18, whereit is discharged which is indicated by illustrating the particle insector 18 half white and half black. It will be explained 'later thatthe particle as shown in sector 18 meets the same conditions as theparticle A in sector 1 so that it is in this manner re-introduced intothe operational cycle.

Sector 3 A fiock material particle A which as shown in sector 2 has beenshot or propelled through one of the openings of the grid-type electrode11 and continues its movement in an upward direction on account of thekinetic energy imparted thereto is now under the diversified influenceof all the electrostatic fields II-VII. Upon reaching the planecomprising the paths of the filaments 29 it may be subject to one ofseveral possibilities. The first possibility is illustrated in sector 3,namely the possibility that this particle A directly hits or makescontact with one of the filaments 29. It may be partly .or wholly'discharged upon contact but in any case it will be attached to theparticular filament on the side facing the electrode 11 on account ofthe adhesive coating of the filament.

Sector 4 A second possibility is illustrated in sector 4. In this case,the positively charged particle A does not directly hit a filament 29bu-t it tends to pass by the filament 29 on its right lhand side soclosely that the forces of attraction between the positively chargedparticle A and the filament carrying quasi-ground potential or negativepotential take effect so that in allprobability the rear end of thisparticle makes contact with the particular filament 29 whereby furtherupward movement of this particle is stopped.

Sector 5 Now the force of gravity in addition to electrostaticattraction by one or the other of the neighbouring filaments 29 causesthe particular iiock material particle to tilt over and to assume forinstance a position as shown in sector 5. However, likewise otherpositions may result as illustrated by Way of example in sectors l2 and13. Already from the above it can be seen that the various 7 particles Aof short pieces of elongated fibrous material will be attached to theadhesive-coated filament 29 in a great number of different positionsoriented radially in many directions relative to the particularfilament.

Sector 6 A further possibility consists in the particular fiock materialparticle A passing at comparatively high speed exactly in the middlebetween two neighbouring filaments 29 so that the attractive forces ofthese two filaments compensate each other. Consequently, this particlebeing still positively c-harged will travel under the influence of atleast the electrostatic fields IV and VI in upward direction. Again,there are various possibilities. The first possibility is that as shownin sector 6 the particle passes through one of the openings of thesecond grid-type electrode 30 which carries negative or groundpotential. If the particle passes more or less exactly through thecenter of that opening of the electrode 30 its movement will continue inupward direction toward the top wall of the housing 1.

Sector 7 The top wall of the housing 1 carries ground i.e., negativepotential. Consequently, when the flock material particle A impinges onthe grounded top wall it is discharged.

Sector 8 As a consequence, the completely discharged particle is nowsubjected only to the torce of gravity G and drops in direction towardthe electrode 30.

Sector 9 The possibility that the dropping particle A cornes to rest ona solid portion of the grid-type electrode 30 is not illustrated in thediagram because it is without any interest in the context of theconsideration of the electrostatic phenomena. As mentioned furtherabove, the electrode 30 is continuously vibrated so that it is to beexpected that sooner or later such a particle will be moved into aposition where it will fall through one of the openings of the electrode30. This, however, is a condition identical With that existing when thedropping particle as illustrated in sector 8 drops directly through oneof the openings of the electrode 30. If, on its downward path, it makesdirect contact with one of the filaments 29 it will become attac-hedthereto on account of the adhesive coating thereof, and assume aposition similar to those illustrated in sectors 11-13, 15, and 16.However, it might as well drop further down, passing between twoneighbouring filaments 29 and reach the region of the positively chargedelectrode 11. It may make contact directly with a solid portion of theelectrode 11 or be attracted thereto, in either case it will immediatelybe charged to positive potential thereby. Consequently, having now thesame polarity as the electrode 11, it will be subject to repulsiveforces K so that this particle is again accelerated in upward .directionas indicated in sector 9. In addition at least the electrostatic field1I takes effect because the filaments 29 carry quasiground or actualground potential whereby the positively charged particle is attracted.

Sector If this particle which was started in upward direction as shownin sector 9 directly hits a filament 29 as s-hown in sector 10 it willbe rattached to its lower side in the same manner as has been discussedabove in reference to the occurrences in sectors 2 and 3. However, alsothe conditions discussed and explained above in reference to sectors 4and 5 may take place so that the particle may be attached to filaments29 in the manner illustrated in sectors 5, 12, 13, 15 or 16. Actually,the particle illustrated in sector 9 is under the diversified influenceof all the fields II-VII.

8 Sectors 11, 12 and 13 As mentioned above, sectors 11, 12 and 13illustrate various positions which the particle A may assume after beingattached to one of the filaments 29 after it has passed closely by oneof these filaments as explained above in reference to sectors 4 and 5.

Sector 14 The particle A as discussed in reference to sector 9 maycontinue its movement in upward direction beyond the plane of thefilaments 29 and reach the region of the second electrode 30.

Again it may pass through one of the openings thereof, in which case,the conditions will prevail which have been discussed above in referenceto sectors 6-8. However it may as well make contact with a solid portionof the grid-type electrode 30l as illustrated in sector 14. Since theelectrode 30 carries ground, i.e. negative potential, the positivelycharged particle A will be discharged upon contact with the electrode 30and will be neutralized in the same manner as described above inreference -to sectors 7 and 8. Consequently, all the consequences maytake place which have been described above in this connection. At leastthe particle shown in sector 14 will be subjected to the force ofgravity G so that it will drop down with the consequence that it iseither directly attached to one of the filaments 29 or reaches again thearea of the electrostatic fields I and Il, in which case it re-entersthe operational cycle described above.

Sectors 15 and 16 The conditions existing in sectors l5 and 16 have beendiscussed above so that no repetition -is needed at this point.

Sector 17 As mentioned already further above, in connection with theoccurrences in sectors 1 and 2, sector 17 illustrates the conditionsexisting when the particle A accelerated in upward directions so as tomove from the top surface of the conveyor 8 toward the electrode 11,would make contact with a solid portion of the electrode 11. If thisshould occur, the particle is also immediately charged to the positivepotential of the electrode 11. Consequently, it Will be repulsedtherefrom, and simultaneously subjected to the force of gravity asindicated by the arrow and the symbols K and G. Thus, it is rapidlyreturned to the top surface of the conveyor 8.

Sector .7 8

As indicated in sector 18 the particle is consequently discharged and isin the same condition which has been described in reference to sector 1.Thus, it will be re-introduced into the cycle of operation.

Sector 19 The illustration in sector 19 is intended only to show that inview of the above various possibilities at least those ock materialparticles A which hit directly one of the filaments 29 will be attachedthereto in opposite directions, one at the lower side and one at theupper side of the particular filament.

Sector 20 Finally the illustration in sector 20 is intended to show thatas a result of all the above described electrostatic effects on thethousands or millions of particles A, it can be safely expected that afilament 29 will be covered from all sides with flock material particlesexactly as was desired at the outset.

Of course, it will be understood that not all the particles Iwill travelstrictly along straight vertical lines upward or downward. There mayalso be collisions between particles, a reflection of mechanical natureof a particle when it hits the inclined top surface of the housing 1 andthe like. However, these irregularities of movements do not affect inany way the general operation according to the method devised by theinvention. In addition, it must be borne in mind that the individualparticles as they rnove around within the housing 1 are in a varyingmanner subjected to the varying influences of the various electrostaticfields I-VII, the effects on individual particles are superimposed uponeach other in varying degrees at different points within the housing 1.All these accumulated effects serve advantageously the main purpose andobject of the invention, namely to cause a more or less uniformapplication of flock material to all sides of the individual filamentsor the like.

It should be noted that it is a great advantage of the present inventionthat actually all the potential differences or electrostatic fieldswhich are utilized in the process are generated by the positive chargeof only one electrode, namely the grid-type electrode 11. All otheractive members of the arrangement which take partV in the electrostaticaction namely the conveyor 8, electrode 30 and the top wall of thelhousing 1 carry ground, i.e. negative potential. The filament materialitself contributes to the electrostatic action inasmuch as it eithercarries quasiground potential or, if the filament material isconductive, ground potential like the above-mentioned electrode 30.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other tppes of amethod and apparatus for electrostatically applying fiock material tomaterial of a diameter comparatively small relative to its length,differing from the types described above.

While the invention has been illustrated and described as embodied in amethod and apparatus for electrostatically applying flock material toadhesive-coated filament material, it is not intended to be limited tothe details shown, since various modifications and structural changesmay be made without departing in any way from the spirit of the presentinvention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this in-ventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A method of electrostatically applying fiock material toadhesive-coated material of a diameter comparatively small relative toits length, comprising the steps of:

orienting the adhesive-coated material longitudinally in a predetermineddirection along a predetermined area of treatment;

introducing particles of flock material into a region extendingsubstantially parallel with said predetermined direction and spaced intransverse direction from said adhesive-coated material;

subjecting said particles of flock material to a high potential firstelectrostatic field which is stationary in space and so directed thatsaid particles of flock material are moved with substantial accelerationin said transverse direction toward said adhesive-coated material sothat those of said particles which make contact with saidadhesive-coated material are attached thereto due to the action of theadhesive coating thereof while those other particles which have missedsaid adhesive-coated material are moved due to the kinetic energyimparted thereto beyond and past said adhesive-coated material;

and subjecting said other particles of flock material which have beenmoved beyond said adhesive-coated material to at least one otherelectrostatic field which is stationary in space and so directed thatsaid other particles are caused to reverse their direction of movementand to move in opposite direction toward said adhesive-coated materialso that those of said other particles which make contact with saidadhesivecoated material are attached thereto due to the action of saidadhesive coating while the remaining ones of said other particles whichhave again missed said adhesive-coated material are caused to be againsubjected tothe action of said first electrostatic field.

2. A method of electrostatically applying fiock material toadhesive-coated filament material, comprising the steps of:

moving the adhesive-coated filament material longitudinally in apredetermined direction along a predetermined path through apredetermined area of treatment;

introducing particles of ock material into a region extendingsubstantially parallel with said predetermined path and spaced intransverse direction from said adhesive-coated filament material;

subjecting said particles of fiock material to a high potential firstelectrostatic field which is stationary in space and so directed thatsaid particles of flock material are moved with substantial accelerationin said transverse direction toward said adhesive-coated filamentmaterial so that those of said particles which make contact with saidadhesive-coated filament material are attached thereto due to the actionof the adhesive coating thereof while those other particles which havemissed said adhesive-coated filament material are moved due to thekinetic energy imparted thereto beyond and past said adhesive coatedfilament material;

and subjecting said other particles of flock material which have beenmoved beyond said adhesive-coated filament material to at least oneother electrostatic field which is stationary in space and so directedthat said other particles are caused to reverse their direction ofmovement and, to move in opposite direction toward said adhesive-coatedfilament material so that those of said other particles which makecontact with said adhesive-coated filament material are attached theretodue to the action of said adhesive coating while the remaining ones ofsaid other particles which have again missed said adhesive-coatedfilament material are caused to be again subjected to the action of saidfirst electrostatic field.

3. A method of electrostatically applying fiock material toadhesive-coated filament material, comprising the steps of:

moving ad-hesive-coated filament material having substantially groundpotential in longitudinal direction thereof along a predetermined paththrough a predetermined zone of treatment;

maintaining in a first limited area extending substantially parallelwith said direction of movement but being spaced in transverse directiona predetermined distance from said path of said filament material afirst electrostatic field which is stationary in space, saidelectrostatic field having a first gradient in said transverse directionbetween a first boundary having high positive potential and a secondboundary having negative lpotential;

introducing fiock material into the region along said second boundaryhaving negative potential so as to cause particles of said fiockmaterial to be moved by electrostatic attraction with substantialacceleration in said transverse direction to said first boun' daryhaving high positive potential and to be moved due to said accelerationfurther beyond said first boundary toward said filament material so thatany thus moved particle of flock material which makes contact with saidfilament material is attached thereto by the action of the adhesivecoating thereof, while 1l those other flock material particles whichhave missed said filament material are moved due to the kinetic energyimparted thereto beyond said path of said filament material; and

maintaining in a second limited area adjacent to said first area andencompassing said zone of treatment and said path of said filamentmaterial at least one second electrostatic field which is stationary inspace, said electrostatic field having a second gradient in saidtransverse direction between said first boundary which is common to bothsaid areas and has high positive potential, and a third boundary havingnegative potential, the direction of said second gradient being oppositeto that of said first gradient, so as to cause said other flock materialparticles which have been moved beyond said path of movement of saidfilament material to reverse their movement and to move in oppositedirection toward said filament material so as to be attached thereto asfar as they make contact therewith, while those of said other particleswhich again miss said filament material are caused to return to eitherone of said first and second boundaries of said first electrostaticfield and to repeat their movement toward said filament material.

4. Apparatus for electrostatically applying fiock material particles toadhesive-coated filament material, comprising, in combination, groundedconductive enclosure means; moving means for moving adhesive-coatedfilament material at substantially ground potential in longitudinaldirection thereof along a predetermined path through a treatment zonewithin said enclosure means; negatively charged support means arrangedin said enclosure means and extending below said predetermined pathspaced therefrom in transverse direction, said support means having atop surface in substantial parallelism with said path and adapted forcarrying fiock material particles thereon; aperture-defining firstelectrode means through which said flock material particles are adaptedto pass and arranged to apply an electrostatic charge to such particles,said first electrode means extending substantially parallel with saidpath substantially midway between said top surface and said filamentmaterial; means for establishing between said support means and saidfirst electrode means a first electrostatic field having a firstgradient in said transverse direction for effecting movement of saidflock material particles in said transverse direction and at substantialacceleration from said support means through said first electrode meansand toward said filament material so that those particles which makecontact therewith are attached thereto, while other particles which failto contact said filament material move beyond the latter; secondelectrode means extending in said enclosure means in substantialparallelism with said path upwardly spaced therefrom in said transversedirection, said second electrode means having a plurality of openingsand being arranged to apply an electrostatic charge to said other flockparticles; and means for establishing between said first and secon-delectrode means a second electrostatic field having a second gradientopposite to said first gradient for effecting reversal of the movementof said other fiock particles to thereby cause the same to move inopposite direction toward said filament material, whereby those of saidother flock particles which contact said filament material becomeattached thereto, whereas the remaining flock particles which fail tocontact said filament material are again subjected to the action of saidfirst electrostatic field.

5. Apparatus for electrostatically applying flock material toadhesive-coated filament material, comprising, in combination,

grounded conductive housing means;

moving means for moving adhesive-coated filament material inlongitudinal direction thereof along a predetermined path through apredetermined zone of treatment located within said housing means:

means for applying to said filament material substantially groundpotential;

at least partly conductive support means arranged in said housing meansand extending substantially parallel with and underneath saidpredetermined path and spaced therefrom in transverse direction apredetermined distance, for carrying flock material on its top surface;

means for applying negative potential to said support means; grid-typefirst electrode means through which said flock material is adapted topass, said first electrode means being arranged for applying anelectrostatic charge to said fiock material and extending substantiallyparallel with said top surface of said sup-port means and substantiallymidway between the latter and said predetermined path of said filamentmaterial;

means for applying high positive potential to said gridtype electrodemeans so as to establish a first electrostatic field between saidsupport means and said first electrode means and having a firstlgradient in said transverse direction and so directed that flockmaterial particles are moved from said support means with substantialacceleration through said grid-type first electrode means toward saidfilament material so that those -particles which make contact therewithare attached thereto while those other particles which have missed saidfilament material are moved beyond and past the latter; second electrodemeans having a plurality of openings,

said second electrode means extending in said housing substantiallyparallel with and above said predetermined path of said filamentmaterial and spaced therefrom a predetermined distance in saidtransverse direction; and means for applying negative potential to saidsecond electrode means arranged for applying an electrostatic charge tosaid other particles and so as to establish a second electrostatic fieldbetween said first and second electrode means and having a secondgradient opposite to said first gradient and so directed that said otherfiock material particles are caused to reverse the direction of theirmovement and to move in opposite direction toward said filament materialso as to be attached thereto as far as they make, contact herewith,while those of said other particles which miss said filament materialagain are caused to be again subjected to the action of said firstelectrostatic field. 6. Apparatus as claimed in claim 5, wherein saidhousing means are constructed as a Faraday cage.

7. Apparatus as claimed in claim 6, wherein said gridtype firstelectrode means is provided with openings larger than the openings ofsaid second electrode means.

8. Apparatus for electrostatically applying flock material toadhesive-coated filament material, comprising, in combination,

grounded conductive housing means; moving means for movingadhesive-coated filament material in longitudinal direction thereofalong a predetermined path through a predetermined zone of treatmentlocated within said housing means;

means for applying to said filament material substantially groundpotential;

at least partly conductive conveyor means arranged in said housing meansand extending substantially parallel with and underneath saidpredetermined path and spaced therefrom in transverse direction apredetermined distance, for carrying fiock material on its top surfacethrough said housing;

means for applying negative potential to said conveyor means;

grid-type first electrode means through which said flock material isadapted to pass said rst electrode means Ibeing arranged for applying anelectrostatic charge to said flock material and extending substantiallyparallel with said top surface of said conveyor means and substantiallymidway between the latter and said predetermined path of said filamentmaterial;

means for applying high positive potential to said gridtype electrodemeans so as to establish a rst electrostatic leld between said conveyormeans and said first electrode means and having a first gradient in saidtransverse direction and so directed that flock material particles aremoved from said conveyor means with substantial acceleration throughsaid gridtype first electrode means toward said filament material sothat those particles which make contact therewith are attached theretowhile those other particles which have missed said filament material aremoved beyond and past the latter;

second grid-type electrode means arranged for applying an electrostaticcharge to said other particles, and eX- tending in said housing below awall of said housing means and substantially parallel with and abovesaid predetermined path of said filament material and spaced therefrom apredetermined distance in said transverse direction; and

means for applying negative potential to said second means and a thirdelectrostatic field between said first housing means so as to establisha second electrostatic ield between said first and second electrodemeans and a third electrostatic field between said first electrode meansand said wall of said housing means, said fields having a second and athird gradient, respectively, opposite to said iirst gradient and sodirected that said other flock material particles are .caused to reversethe direction of their movement and to move in opposite direction towardsaid filament material so as to be attached thereto as far as they makecontact therewith, while those of said other particles which miss saidfilament material 4 again are caused to be again subjected to the actionof said first electrostatic field. 9. Apparatus as claimed in claim 8,including vibrator means for applying oscillatory movement to said firstand second grid-type electrode means.

10. Apparatus as claimed in claim 9, wherein said housing means areconstructed as a Faraday cage.

11. Apparatus as claimed in claim 10, wherein said rst grid-typeelectrode is provided with openings larger than the openings of thesecond grid-type electrode.

12. Apparatus as claimed in claim 9, wherein said first grid-typeelectrode is provi-ded with openings larger than the openings of thesecond grid-type electrode.

13. Apparatus as claimed in claim 8, wherein said housing means areconstructed as a Faraday cage.

14. Apparatus as claimed in claim 12, wherein said first grid-typeelectrode is provided with openings larger than the openings of thesecond grid-typeelectrode.

15. Apparatus as claimed in claim 8, wherein said first grid-typeelectrode is provided with openings larger than the openings of thesecond grid-type electrode.

References Cited UNITED STATES PATENTS Re. 22,419 1/1944 Smyster 117-172,047,525 7/1936` Thode 117-17 2,152,077 3/1939 -Meston et al 117-172,173,032 9/1939 Wintermute 117-17 2,174,328 9/1939 Meston et al. 117-172,276,328 3/1942 Melton 118-627 2,675,330 4/1954 Schwartz et al. 117-33X 2,698,814 1/ 1955 Rausburg 118-624 X 2,976,839 3/1961 Okma et al.118-624 X 3,096,213 7/ 1963 McCurtain 118-638 2,986,473 5/ 1961Ritzerfeld et al. 117-17 X FOREIGN PATENTS 479,254 12/1951 Canada.1,002,725 2/ 1957 Germany.

337,486 5/ 1959 Switzerland.

0 WILLIAM D. MARTIN, Primary Examiner.

MURRAY KATZ, Examiner.

E. I. CABIC, Assistant Examiner.

